The split between establishment Republicans and their tea party brethren over debt limit strategy boiled over on the Senate floor Wednesday, when GOP leaders scrambled to put down a filibuster threat by Sen. Ted Cruz, R-Texas.

As he did in last year's shutdown showdown, Cruz had been pushing his fellow Republicans in both chambers to dig in on the debt limit and extract concessions from President Barack Obama.

But McConnell privately counseled his fellow senators that such a path — which could have led to another shutdown and a first-ever default — was folly. At the heart of the dispute is what will play best in the midterm elections as the GOP attempts to regain control of the Senate.

"The challenge is we all knew what was going to happen after the House did what they did, and you know, to me, the most important thing that can happen this year is ... for Republicans to win the majority in November," Cornyn told CQ Roll Call after the vote. "I don't want to do anything that would interfere with that."

Both McConnell and Cornyn face primary challenges in the coming months.

Cruz and McConnell had sparred at the GOP's Tuesday policy lunch, which some attendees described as heated.

“The leader thought we should go ahead and not have a government shutdown and I agree with him on that," said Sen. Mark S. Kirk of Illinois. "A government shutdown is a political mistake for Republicans.”

Cruz, for his part, ripped what he considered to be a capitulation.

"Today's vote is yet another example that establishment politicians from both parties are simply not listening to the American people," he said. "Let's be clear about the motive behind this vote — there are too many members of Congress who think they can fool people and they will forget about it the next week. But sometimes, come November, the people remember."

Several colleagues lauded Cornyn and McConnell for walking the plank on the procedural measure, even though they ultimately voted against lifting the ceiling. But their primary opponents and conservative groups quickly attacked the Republicans for their cloture votes.

Cornyn dismissed the critics: "I've been around politics long enough to know that people will lie, and so will people lie about it and try to misrepresent it? Yeah. Sure. But I think that I'm comfortable with the truth."

The Texas Republican also ignored the procedural vote when issuing a news release proudly touting his vote against the final passage of lifting the debt limit.

A GOP Senate aide said Cruz's position was "about forcing people to show their true colors, having people take honest votes that show where they want to be." The aide said the day's events led to the conclusion that "today was the day that broke” McConnell.

Before McConnell and Cornyn cast their decisive "aye" votes, they worked their fellow Republicans, but the total was stuck just below the magic 60th vote.

After the voting, Republican senators clustered together on the floor. The scrum featured a band of Republicans often known to stick their necks out on difficult procedural votes, including Lisa Murkowski of Alaska and Susan Collins of Maine, as others popped in and out.

But this time, it appeared that the usual suspects balked at going it alone.

Murkowski declined to provide any details on the floor discussions, but conceded, “Let's just put it this way, nobody likes to be 60."

She said that for the GOP senators, “it was very important to see that you had the leadership team, almost 100 percent of the leadership team, stepped forward and said you know, it's important that we get this issue behind us, and, and they led.”

The bill was approved on a party line vote, 55-43, shortly after the vote to invoke cloture on the bill. The legislation appeared in doubt until GOP Sens. John McCainof Arizona, Jeff Flake of Arizona, Orrin G. Hatch of Utah and John Thune of South Dakota emerged from the GOP cloak room and voted "aye" — after Cornyn and McConnell had taken the plunge.

"Some times you do what you've got to do," Flake said.

While Republicans needed to provide only five votes to reach the 60 needed to cut off debate on debt ceiling proposal, ultimately a dozen Republicans voted to clear the hurdle.

The outcome was still in question coming out of a GOP lunch just as the vote was starting Wednesday, with both Flake and Thune, the conference chairman, indicating that the votes weren’t there yet.

McCain joined in the praise of leadership.

“It was very helpful that the leadership voted the way they did,” the Arizona Republican said. “It was a very courageous act, especially [for] Sen. McConnell, who we all know is in a tough race.”

Kirk said the Republican leaders did what needed to be done, describing them as “leaders who led.”

Sen. Lindsey Graham, R-S.C., who has his own primary challenger from the right and voted against advancing the bill, also tipped his hat to the Republicans who cast "ayes."

“From their point of view they did what they though was best for the party and the future of the caucus," he said. "I think people appreciate that."

He also blamed House Republicans for putting Senate Republicans in such a bad spot by not being able to come together on a concession in exchange for suspending the debt ceiling.

“This is the result of not having a plan,” Graham said. “Guys in the House need to find something reasonable to ask for to raise the debt ceiling and the Senate needs to be supportive.”

McCain agreed that, given the threat of a default, the Senate was left little choice by the House.

He also noted that a government shutdown as a result of not being able to borrow money to fund government programs would hurt Republicans, just like the shutdown in October that resulted from the effort by some GOP senators — most notably Cruz — to defund Obamacare.

“Some of us had pointed out that ... the government shutdown [in October] was very harmful,” McCain said. “If it had not been for the troubled rollout of the website for Obamacare it would have been disastrous for us.”

And “it was obvious that the House of Representatives wasn’t going to vote any different,” McCain continued.

McCain was careful not to pin any blame on Cruz, with whom he has butted heads in the past.

“I respect Sen. Cruz’s right to exercise his rights as a senator, I’m not going to complain about that,” McCain said. “I think when we have open and honest debate ... I hope those differences are not personal.”

Democrats, meanwhile, merely breathed a sigh of relief.

"I am glad they did the responsible thing," said Sen. Patty Murray, D-Wash., chairwoman of the Budget Committee. "It was painful to watch."